To prepare shrimp, combine the first 3 ingredients in a small skillet over medium heat; cook 2 minutes or until fragrant, stirring constantly. Cool. Place the spice mixture in a spice or coffee grinder; process until finely ground.
Combine spice mixture, yogurt, and next 6 ingredients (through ground red pepper) in a large zip-top plastic bag. Add shrimp to bag; seal. Toss to coat. Marinate in refrigerator 1 hour, turning bag occasionally.
Combine onion wedges, bell pepper, and tomatoes in a large bowl. Drizzle with oil; toss to coat.
Remove shrimp from bag; discard marinade. Thread 4 shrimp, 2 tomatoes, 2 onion wedges, and 2 bell pepper pieces alternately onto each of 8 (10-inch) skewers. Lightly coat skewers with cooking spray. Place skewers on grill rack coated with cooking spray. Grill 4 minutes on each side or until done.
To prepare chutney, combine mint and remaining ingredients in a food processor; process until smooth. Serve with skewers.